Say time of 90 date, 97 93 date, petrolic that do not have lead when us, do you know the meaning of these benzine grade?
Alleged 90, 97 93 date, benzine that do not have lead, it is the antiknock shake capability that shows they contain 90 ％ , 93 ％ , 97 ％ respectively is strong " isooctane " , the antiknock shake ability that contains 10 ％ , 7 ％ , 3 ％ respectively that is to say is poor age alkyl. Then the discretion of octane number became gasoline engine to be opposite the index of discretion of antiknock shake ability. Should use 97 petrolic motor, if use 90 gas, easy of course generation explodes shake.
Engine compression ratio and explode shake
At present the car is used most is so called 4 strokes engine, it is to use a piston to be in air cylinder reciprocate, with " into gas, compress, erupt, exhaust " 4 journeys, inspiratory benzine and airy mixture, compress it next, reoccupy sparkplug is nodded explode it and gain momentum, after gaining momentum, again the waste gas after eduction dot explodes.
Above all what we should understand is, the fuel that 4 strokes engine uses is not benzine certainly, compress natural gas, liquefied petroleum gas, even alcohol, can use the fuel that serves as engine. Benzine can make main fuel, because it is obtained relatively easily,be, store more easily, relative to valence cheap.
Can using a variety of fuel because of engine, accordingly, in the beginning of engine develops, engineers also had made a lot of attempts, besides attempt engine different design can have different property besides, also try to use the result that different fuel can get what differs. Result discovery, when other condition is changeless, should raise the compression ratio of engine so that heal only tall, can get greater horse power is outputted. However, compression ratio can not raise without limit however, when compression ratio is carried too high, engine can appear explode shake phenomenon. Alleged explode shake, it is the oil that the course compresses or gas mixture, before sparkplug has not ignited, the high fever that the aeriform element campaign that creates because of place of journey be compressioned produces is ignited, form phenomenon of so called spontaneous combustion, subsequently sparkplug is ignited again again compress oil or enrage mixture, cause two groups to explode high bolide is acuteness in firebox collision, if knock,arise consequently general " noise made in coughing or vomiting, noise made in coughing or vomiting, noise made in coughing or vomiting " sound. Through careful research, engineers discover, explode so shake is concerned with the choice of fuel again, if choose,was opposite fuel, so although raise engine compression ratio, also won't happen explode shake.
Explode shake and octane number
Knew to explode after the relation of shake and fuel, engineers begin to produce the place in refinery, all sorts of oil plants one by one that can serve as engine take test and test, result discovery, antiknock shock effect is the poorest is " age alkyl " , because of this engineers the strongest aseismatic index 100 gave isooctane, and the poorest age alkyl gave it an aseismatic index of 0. Then, begin from now on, the discretion of octane number became gasoline engine to be opposite the index of discretion of antiknock shake ability.
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